亚致死剂量的夫西地酸与氯霉素对大肠杆菌转录与翻译偶联的抑制作用研究

由于多重耐药菌的不断出现以及新抗生素的研发滞后，人类正在经历严峻的抗生素危机。亚致死剂量的抗生素环境是细菌耐药性传播的重要促进因素。近年来研究表明：抑制蛋白质翻译的抗生素在亚致死剂量下，通过致使细菌体内大量核糖体失活进而抑制细菌增殖，然而核糖体失活的机制尚不明确。前期的实验结果发现：亚致死剂量的夫西地酸可以显著降低细菌核糖体翻译延伸速率，但不影响mRNA转录延伸速率，暗示转录与翻译解偶联现象的发生。解偶联可能造成转录提前终止，进而造成核糖体翻译流产。本项目将建立转录与翻译偶联作用的定量研究方法，在此基础上系统研究夫西地酸与氯霉素对大肠杆菌转录与翻译偶联的抑制效应。项目将阐明转录与翻译解偶联对基因表达的影响及其与核糖体失活的内在联系，加深人们对抗生素体内作用机制的理解，为未来指导抗生素合理用药与开发新型抗生素提供理论依据。

Human beings are currently faced with severe antibiotic crisis because of the continuous emergence of multi-drug resistance bacteria and the lagging-behind of new antibiotics development. The environment of sublethal doses of antibiotics is an important factor that promotes the spread of bacterial drug resistance. Recent studies have shown that sublethal doses of translation-blocking antibiotics inhibit bacterial growth through inactivating a large fraction of ribosomes in vivo. However, the underlying mechanism of ribosome inactivation remains unclear. Preliminary data have demonstrated that sublethal doses of fusidic acid dramatically reduce the ribosome translational elongation rate, but have no effect on the mRNA chain elongation rate, indicating the occurrence of transcription-translation uncoupling. The transcription-translation uncoupling may cause transcription premature termination, further resulting in ribosome translation abortion. This proposal aims to establish the quantitative methodology for studying transcription-translation coupling, further systematically investigating the inhibitory effect of fusidic acid and chloramphenicol on the bacterial transcription-translation coupling. This research will elucidate the effect of transcription-translation uncoupling on gene expression as well as its relation with the ribosome inactivation. We expect that the related findings can deepen our current understanding on the in vivo mechanism of antibiotics, further laying the theoretical foundation for guiding the rational administration of antibiotics and new antibiotics development in the future.